Britons watching pro-jihadist Youtube videos last week may have received pre-roll campaign messaging from none other than Theresa May, London's Sunday Times reported, leading Britain's three largest political parties to pull all YouTube advertising before tomorrow's general election.

Election adverts for Labour and the Lib Dems also ran on a YouTube channel created by a supporter of Islamic State. Tim Farron, the Liberal Democratic leader, was pictured above the supporter's profile picture, an image of the terror group's black flag.

YouTube channels must now garner 10,000 views before they can "monetize" videos with advertisements and, YouTube said earlier in the crisis, get an application approved.. But popular pro-jihadist content, namely al-Rashed's sermons, have attracted millions of views. YouTube "sources" say these extremists receive no advertising money, The Times reported.

The news attracted renewed calls for YouTube, and its owner Google, to block extremist content on the site.

Yvette Cooper, a former chairwoman of a U.K. Parliamentary committee, asked the question many British politicians are likely wondering: "What the hell are Google doing?"